Apparatus for producing a metal workpiece by cold extrusion



Sept. 15, 1959 BERGONZO 2,903,924

APPARATUS FOR PRODUCING A METAL WORKPIECE BY COLD EXTRUSION Filed April 16, 1956 v 4 Sheets-Sheet l Sept. 15, 1959 P; BERGONZO APPARATUS FOR PRODUCING A METAL WORKPIECE BY COLD EXTRUSION Filed April 16, 1956 4 Sheets-Sheet 2 fi /r Sept. 15, 1959 P. BERGONZO 2,903,924

APPARATUS FOR PRODUCING A METAL WORKPIECE BY COLb EXTRUSION Filed April 16, 1956 4 Sheets-Sheet 3 N 701E B 8: QBE/PGQA/ZO Sept. 15, 1959 P. BERGONZO 2,903,924

APPARATUS FOR PRODUCING A METAL WORKPIECE BY cow EXTRUSION Filed April 16, 1956 4 Sheets-Sheet 4 so. 59% s2 s1 45 E 3 2 45 28 29 16 53 B 44 7 3o g 29 3 2 w 's 22- A 7 3 46 924 25 kke BERGoA/Z'a BY M M United States Fatent APPARATUS FOR PRODUCING A METAL WORK- PIECE BY COLD EXTRUSION Pierre Bergonzo, Geneva, Switzerland, assignor to Tarex S.A., Geneva, Switzerland, a limited-liability stock company of Switzerland Application April 16, 1956, Serial No. 578,289

Claims priority, application Switzerland April 20, 1955 10 Claims. (Cl. 78-69) The present invention relates to a process for producing a metal workpiece by cold extrusion, which is distinguished from known processes in that the metal is subjected to a gradual pressure by compressing a liquid, and then, during the extrusion of the metal contained in a mould whose two parts are displaceable relatively to one another, sufiicient pressure is maintained on the said metal to oblige it to flow and to assume the shape of the mould, by causing the two parts of the mould to be displaced relatively to one another by allowing the said liquid under pressure to expand.

The invention also relates to an installation for carrying the process into effect, comprising a press equipped with a presser member and a support member, the said installation being characterised in that at least one of the two aforesaid members of the press is connected to a device for applying pressure to a liquid constituting a hydraulic spring means for causing the rapid relative displacement of the said members during the extrusion of the metal.

Some forms of embodiment of an installation for carrying the process into effect are illustrated diagrammatically and by way of example in the accompanying draw- Fig. l is a diagram of the mechanical and hydraulic connections of the installation.

Fig. 2 is a plan view of the press, some parts being broken away and others shown in section.

Fig. 3 is a sectional view taken on the line IIIIII of Fig. 2. I

Fig. 4 is a sectional view taken on the line IVIV of Fig. 3.

Figs. 5 and 6 are sectional views of details, on a larger scale.

Figs. 7 and 8 are diagrammatic partial views of two other forms of embodiment of the installation.

According to Figs. 1 to 4, of the accompanying drawings, the installation comprises a motor M which drives, through a belt transmission, one of the parts 1 of a clutch. The said part 1 rotates freely on a shaft 2 carried in bearings 3. The second part 4 of the said clutch is displaceable axially along thesaid shaft 2, but is angularly fixed with the said shaft. A toothed wheel 5, which is fixed rigidly to the shaft 2, meshes with a large toothed wheel 6 which is fix'ed rigidly on a shaft 7 rotatable in bearings 8 and carrying a crank 9 A connecting rod 10 mechanically connects the said crank to one end of a two-armed lever 11 whose other end is con nected by a linkage 12 to a piston 13 slidable in a cylinder 14. Said cylinder is connected by pipes 15 to pres= sure-cylinders 16 filled with liquid. Valves 17 enable one or more cylinders 16 to be brought into operation. The lever 11 pivots on a pin 18 which is fast with a slide 19 slidable in guideways 20. A presser member 21 which is carried by a guide 22 rigidly connected to the slide 19, carries one of the parts 23 of a tool, whose second part 24 is carried by a support member 25.

The piston 13 carries a rod 26 slidable in a-guide 27' ree and carrying a threaded portion 28 which is engaged in a nut 29 held in a fixed angular position. A worm wheel 30 formed in the peripheral surface of the said nut, meshes with a worm 31 fast with a shaft 32 rotatable in a bearing 33 and carrying a control member 34. The upper face 35 of the said nut, abutting against a bearing surface 36, defines the upper end position of the piston 13.

The linkage 12 comprises two connecting rods arranged one on either side of the lever 11 and fixed to the two ends of a shaft 37 which is freely rotatable in a bearing 38 provided on one of the ends of the said lever 11. The lower ends of the said connecting rods 12 are pivoted freely on two lateral journal's 39 fast with a push member 40 slidable in a guide 41. The piston 13 is connected to the said push member by a coupling consisting of a circular neck 42 in which engages a collar 43 rigidly fastened to the push member 40. The end 44 of the piston rod is of spherical shape and co-operates with a support face 45 carried by the push member.

The connect-ing rod 10 is freely pivotable on the one hand on the pin 46 of the crank 9 and on the other hand on a pin 47 carried by the two arms 48 of the forked extremity of the lever 11.

The tool 23, 24 comprises two parts capable of being displaced relatively to one another and constituting at once a tool for punching and a tool for moulding a workpiece by cold extrusion of metal. To this end, the portion 23 of the tool is constituted by a punch cooperating with a matrix formed in the part 24 of the tool. However, the said matrix is obturated by one 49 of the parts of a mould whose second part is formed by the front face 50 of the punch. Recesses 51 are formed in the said front face and, if appropriate, in the part 49, which correspond to bosses which have to be provided on the finished workpiece.

When the installation is stopped, its members and elements occupy the relative positions illustrated in Fig. l. The pin of the crank 9 is in its extreme upper position, as is also the slide 19, and the push member 40 is in its lower end position.

When the motor M is started up, it drives the part 1 of the coupling in rotational movement. By actuating a control member 52, the user causes the engagement of the two parts 1 and 4 of the said clutch, and the release. of a brake 53, 54. From then onwards, the shaft 2 is; driven in rotation and drives the crank 9 by the inter. mediary of the speed reducing gear 5, 6. Consequently,v the connecting rod 19 is driven downwards and oscillates-v the lever 11 on its pin 18. The piston 13 is then driven: upwards by means of the linkage 12 and the push monber 40, and applies pressure to the liquid contained 111, the cylinder 14 and in the cylinders 16. However, displacement of the piston 13 is very slight or even practically nil, since the liquid is substantially incompressible, so that the piston bears against the said liquid and the downward movement of the rod 10 causes the lever 11 to rock on the shaft 37. The slide 19 is then driven downwards.

The punch 23 comes to bear against a strip of metal 55 which has been placed on the matrix 24, and the pressure exerted by the said punch causes a part 56 to be punched out in known manner. This punched part is pushed by the punch onto the part 49 of the mould housed in the interior of the matrix. At this instant, the punch is stopped in its downwards movement, but since the rod 10 continues to travel downwards the piston 13 It will be apparent that as soon as the metal becomes soft or semi-fluid, the molecules of the metal become displaced relatively to one another and rapid heating is produced, so that in practice the metal suddenly reaches a state of such fluidity that it is hurled into the recesses 51 of the mould.

As a result, the thickness a of the punched part tends to diminish suddenly as well as the pressure inside the mould. The crank 9 continuing its travel downwards is not capable to cause the presser member 21 to be displaced downwards sufiiciently quickly to maintain inside the mould an adequate pressure to keep the metal in the fluid state and to cause the said metal to flow until it assumes the shapes of the internal walls of the mould. On the other hand, the liquid which has been subjected to pressure is capable of expanding very rapidly so that it repels the piston 13 downwards as soon as the pressure in the mould is reduced by the extrusion. The linkage 12, also moved downwards, rocks the lever 11 in the direction of the arrow 1 about the pin 47, thus causing the slide 19 to be displaced rapidly downwards. Consequently, the movable part 23 of the tool is displaced rapidly in the direction of the fixed part 24, and suflicient pressure is maintained inside the mould to keep the metal in the liquid state or at least in a semi-liquid state so that the material of the punched part 56 is hydrostatic and flows into the recesses formed in the walls of the mould, and finally follows the shapes of the said walls and wholly fills the internal cavity of the mould. The crank 9 continues to travel downwards and causes the liquid to be subjected to pressure again until the face 35 of the nut 29 comes to bear against the bearing face 36. At this instant, the rod brings about a final downward movement of the punch 23, which then reaches its lower end position in which the mould is completely closed and determines the exact dimensions of the coldextruded part.

The crank 9 continues its travel, shifts the rod upwards, thus relieving the metal contained in the mould from pressure, so that the said metal solidifies instantaneously. When the crank 9 reaches its upper position, the user pulls on the control member 52 so as to disengage the two parts of the coupling 1, 4 and to operate a brake 53, 54. The cold-extruded part can then be Withdrawn from the matrix and the strip of metal 55 is advanced by one unit so that a new part can be punched and then formed by cold-extrusion as described hereinbefore.

The compression stroke of the piston 13 can be adjusted at will by operating the valve 17, that is to say, by causing the said piston to act on a more or less considerable quantity of liquid.

The piston, cylinder, and liquid cylinders constitute in fact hydraulic spring means whose compression stroke can be regulated so as to obtain, during the extrusion of the metal, rapid displacement of the presser member 21 of sufficient amplitude to cause the metal to flow to the bottom of the mould cavities. Since expansion of this hydraulic spring is extremely rapid, the necessary pressure for maintaining the metal in a hydrostatic condition can be maintained inside the mould during the extrusion of the metal. Owing to the fact that the lower end position of the punch is determined positively by the rod 26 and the nut 29 bearing against its abutment 36, all the extruded workpieces are necessarily of exactly the same thickness.

'By actuating the control member 34, the position of the nut 29 along the threaded portion 28 can be adjusted so as to define a lower end position for the punch in such a way that the whole interior of the closed mould will be filled with metal. It will be apparent that the thickness of the metal strip 55 must be so chosen that the volume of the punched part 56 corresponds to the vol ume of the finished extruded workpiece.

In the alternative form of embodiment illustrated partly in Fig. 7, members and elements already described with reference to Figs. 1 to 6 are given the same referonce numerals. The part 23 of the tool is connected mechanically to the rod 10 by means of the lever 11, whose linkage 12 is articulated to a pin 57 carried by lugs 58 which are rigidly fastened to the press frame. On the other hand, the support member 25, carrying the second part 24 of the tool, is carried by a slide 59 which is slidable in a guide 60. The said slide carries a collar 61 which abuts against a bearing surface 62 formed in the press frame. The said slide also carries'the threaded portion 28 which engages the nut 29 provided with the toothed annulus 30, the latter meshing with the worm 31 which is carried by the shaft 32 provided with its control member 34.

The said threaded portion 28 carries the pistons 13 which is arranged in the cylinder 14 connected by pipes 15 to cylinders 16. A spring 63 tends to hold the part 24 of the tool in its upper position illustrated in the drawing, and defined by the collar 61 bearing against the bearing surface 62.

This second form of embodiment of the installation operates in a substantially similar manner to the installation described with reference to Figs. 1 to 6. In fact, when the punch 23 is driven downwards, it shifts downwards the part 24 of the tool and therefore causes pressure to be applied to the liquid contained in the cylinder 16, until the instant when the pressure reaches a value at which the metal of the punched part 56 becomes hydrostatic. The said metal is then hurled into the cavities of the mould and the pressure in the mould is kept very high by a rapid relative displacement of the two parts of the mould caused by the expansion of the liquid which has been subjected to pressure in the cylinders 16. The punch 23 continues its downward travel and again applies pressure to the liquid in the cylinders 16 until the instant when the face 64 of the nut 29 comes to abut on a hearing surface 65. The crank 9, already very near to its lower end position, causes the punch to be displaced slightly further downwards. This latter movement brings the punch into its lower end position, and the two parts 23 and 24 of the mould are brought into a well-defined closure position. This last displacement of the punch causes a sort of swaging or stretching of the cold-extruded workpiece which imparts to the said workpiece its final form and a clean impeccable appearance.

In the form of embodiment illustrated in Fig. 8, the crank 9 is replaced by a cam 66 acting upon a slide 67 which is displaceable vertically in guides 68. The said slide comprises a cylinder 69 connected by a flexible conduit 70 to pipes 15 which are connected to liquid cylinders 16. A piston 71 is slidable inside the said cylinder 69 and carries the threaded portion 28 which engages in the nut 29 whose axial position can be adjusted by operating the shaft 32. The threaded portion 28 carries the guide 22 which is provided with one of the parts 23 of the tool.

Here again, the lower end position of the punch 23 is determined positively by the cam 66, the face 72 of the slide coming to bear on the upper face 35 of the nut 29. However, it is not absolutely necessary for the lower end position of the punch to be positively defined by the crank 9 or the cam 66 as described with reference to Figs. 1 to 8. Indeed, if by adjusting the characteristic of the hydraulic spring means, for example by opening or closing the valves 17, it is possible to obtain a sufliciently flat characteristic for the said hydraulic spring means to enable the latter to maintain, during extrusion inside the mould, adequate pressure for maintaining the metal in a hydrostatic condition until the internal cavity of the mould is completely filled with metal, then the mould is already completely closed when the hydraulic spring means are detensioned so that it is no longer necessary to provide for subjecting the liquid to renewed pressure -and causing the positive closure of the mould. Also, in

order to obtain the desired characteristic of the hydraulic asoa spring, the liquid in the cylinders can be previously subjected to pressure by means of a compressor so that in the inoperative position (the position illustrated in Figs. 1, 7 and 8) the liquid is already under pressure.

Tests which have been carried out by means of an installation such as has been described hereinbefore, have proved that it is possible to produce workpieces by cold extrusion which comprise markedly projecting portions and which have very complicated shapes, such as known cold extrusion installations cannot produce. This is due to the fact that according to the process which is the subject of the present invention, during the extrusion period suflicient pressure is maintained inside the mould to keep the metal in a hydrostatic condition, by bringing about a rapid relative displacement of the two parts of the mould by the expansion of a liquid which has been subjected to pressure.

I claim:

1. An apparatus for forming a metal disc from a metal strip and cold extruding a workpiece from said metal disc, comprising, in combination, a frame, a support member and a guideway in said frame, a multi-part recessed mold comprising two cooperating members, a plunger slidably positioned within said guideway, one of said mold members being attached to said plunger, the other of said mold members being attached to said support member, means connected to one of said plunger and support members for actuating one of said plunger and support members, each having attached thereto one mold member, and for moving one of said mold members towards the other of said mold members to close said mold and to form said metal disc, hydraulic spring means for causing said actuating and moving means to apply pressure against said so-formed metal disc within said mold to cause the cold flow of the metal of said metal disc and for accumulating energy during the applying of said pressure against said so-formed metal disc and for rapidly relatively displacing one of said plunger and support members. towards the other in releasing said accumulated energy after the beginning of the cold extrusion of the metal within the mold to cause the flow of the metal in assuming the shape of the mold, means connecting said hydraulic spring means to one of said plunger and support members for subjecting said hydraulic spring means to a progressively increasing pressure after the actuation and movement of said one mold member towards said other mold member while said hydraulic spring means is causing said actuating and moving means to apply pressure against said so-formed metal disc within said closed mold, and means for adjusting the capacity of said hydraulic spring means 1121 accordance with the workpiece to be made, whereby the metal IdlSC is formed from the metal strip, the cold flow of the metal of the metal disc is caused within the closed mold, and the metal is cold extruded in a single operation due to oifsetting the sharp drop in pressure applied on the metal within the closed mold brought about by the extrusion of the metal while under pressure within the mold and the maintaining of the flow pressure on the metal within the mold.

2. The apparatus of claim 1 wherein one of said multipart mold members is a punching tool means for punching the metal disc from the metal strip.

3. The apparatus of claim 1 wherein one of said multipart mold members is a punching tool means for punching the metal disc from the metal strip and said actuatlng and moving means is mechanically connected to one of said plunger and support members.

4. The apparatus of claim 1 wherein said actuating and moving means is connected to said plunger member and includes an oscillating two-armed lever hingedly mounted on said plunger member and said hydraulic spring means is connected to the end portion of one arm of said lever.

5. The apparatus of claim 1 wherein said actuating and moving means is connected to said plunger member and includes an oscillating two-armed lever hingedly 6 mounted on said plunger member, said frame has a ing fixed thereon, one arm of said lever is connected to said lug, and said hydraulic spring means is connected to said support member.

6. An apparatus for forming a metal disc from a metal strip and cold extruding a workpiece from said metal disc, comprising, in combination, a frame, a support member and a guideway on said frame, a connecting bar, a plunger connected to said connecting bar, a multi-part recessed mold comprising two cooperating mold members, one of said mold members being attached to said plunger, the other of said mold members being attached to said support member, a guide member for said plunger, said plunger being slidably positioned in and through said guide member, cam means for actuating and moving said plunger toward said support member to close said mold and form said metal disc, an adjustable capacity hydraulic spring means for causing said actuating and moving means to apply pressure against said so formed metal disc within said mold to cause the cold flow of the metal of said metal disc and for accumulating energy during the applying of said pressure against said so-formed metal disc and for rapidly relatively displacing said plunger towards said support member in releasing said accumulated energy after the beginning of the cold extrusion of the metal within the mold to cause the flow of the metal in assuming the shape of the mold, said hydraulic spring means including an open-ended cylinder slidably positioned in said guideway, said cylinder being open at its bottom end and closed at its top end, a piston slidably positioned in said cylinder, and a hydraulic fluid source connected to said cylinder at its top end and into said cylinder above said piston, said piston being connected to said connecting bar, said cam means acting upon the top surface of said cylinder, whereby the metal disc is formed from the metal strip, the cold flow of the metal of the metal disc is caused within the closed mold, and the metal is cold extruded in a single operation.

7. The apparatus of claim 1 including means for limiting the amplitude of the rapid relative displacement of said one of said plunger and support members towards the other by said hydraulic spring means, said means including an abutment member and an abutting member cooperating with said abutment member, said abutment member being on said frame and said abutting member being carried by said means connecting said hydraulic spring means to one of said plunger and support members, and means for regulating said abutting member in the limiting of said amplitude of displacement, whereby said actuating and moving means causes the complete closing of the multi-part mold when said abutting member abuts against said abutment member.

8. The apparatus of claim 4 including means for limiting the amplitude of the rapid relative displacement of said plunger towards the support member, said means including an abutment member and an abutting member cooperating with said abutment member, said abutment member being on said frame and said abutting member being carried by said means connecting said hydraulic spring means to said plunger, and means for regulating said abutting member in the limiting of said amplitude of displacement, whereby said actuating and moving means causes the complete closing of the multi-part mold when said abutting member abuts against said abutment member.

9. The apparatus of claim 5 including means for limiting the rapid movement of said plunger caused by said hydraulic spring, said means including an abutment member and an abutting member in cooperative relation with each other, and means for regulating said abutting member in limiting the amplitude of said rapid movement.

10. The apparatus of claim 6 including means for limiting the rapid movement of said plunger caused by said hydraulic spring means, said means including an 7 abutment member and an abutting member in cooperative relation With each other, and regulating means for said abutting member allowing to choose and to fix the amplitude of said rapid movement.

References Cited in the file of this patent UNITED STATES PATENTS 8 Rode Sept. 27, 1932' Pardee May 30, 1933 Haverbeck July 17, 1934 Treer July 9, 1935 Sentance et a1. Oct. 11, 1938 Rode Sept. 12, 1939 Albers Jan. 31, 1956 Bauer et a1. Aug. 21, 1956 OTHER REFERENCES May 4, 1943. 

